1. Field of Inventive Concepts
The inventive concepts disclosed herein are generally directed to interconnect bridge assemblies used to connect photonic integrated circuit chips and electronic integrated circuit chips. More particularly, but not by way of limitation, the inventive concepts disclosed herein are directed to a high-speed flip-chip interconnect bridge assembly to connect a modulator implemented as a transmitter photonic integrated circuit and a modulator driver supplying electronic signals to the modulator within a wave-division multiplexing optical network. In some exemplary embodiments, the interconnect bridge assembly can also be used to interconnect an optical signal detector implemented as a receiver photonic integrated circuit and a receiver amplifier.
2. Brief Description of Prior Art
Wavelength Division Multiplexing (WDM) optical networks are deployed for transporting data in long haul networks, metropolitan area networks, and other optical communication applications. In a WDM optical network, a plurality of different light wavelengths, representing signal channels, are transported or propagated along optical fiber links or along one more optical fibers comprising an optical span.
In a conventional WDM system, an optical transmitter is an electrical-to-optical (EO) conversion apparatus for generating an integral number of optical channels λ1, λ2, λn, where each channel has a different center or peak wavelength.
DWDM optical networks, commonly have optical transmitter modules that deploy eight or more optical channels, with some DWDM optical networks employing 30, 40, 80 or more signal channels. In the past, the optical transmitter module generally had a plurality of discrete optical devices, such as a discrete group or array of laser sources of different wavelengths, a plurality of discrete modulators, such as, Mach-Zehnder modulators (MZMs) or electro-absorption modulators (EAMs), and an optical combiner, such as a star coupler, a multi-mode interference (MMI) combiner, an Echelle grating or an arrayed waveguide grating (AWG). All of these optical components were optically coupled to one another as an array of optical signal paths coupled to the input of an optical combiner using a multitude of single mode fibers (SMFs), each aligned and optically coupled between discrete optical devices.
The recent development of photonic integrated circuit chips has increased the efficiency of DWDM networks by incorporating multiple previously separate optical components onto a single integrated photonic circuit chip (PIC). PICs have significantly increased the throughput of optical networks and have decreased the size and cost of optical network nodes and components. For an example of a PIC that may be used in a DWDM network see U.S. Pat. No. 8,300,994.
In the case of DWDM networks, modulator driver chips or modulator drivers supply high-frequency electrical signals indicative of data to one or more modulators on the PIC, and the modulators convert the high-frequency electrical signals into optical signals by modulating the light signal outputted by a laser source for each channel or wavelength used by the DWDM network. Modulator drivers are typically separate electronic integrated circuits, such as ASICS, for example, which have multiple output ports (e.g., one for each electrical channel), which are electrically connected with multiple input ports on the PIC to transmit the high-frequency electrical signals (e.g., radio-frequency signals) to the modulators on the PIC. Currently, the connections between modulator drivers and PICs are established by positioning the modulator driver in close proximity to the PIC and connecting multiple pairs of output ports on the modulator driver and input ports on the PIC with a plurality of conductive wire bonds between each pair of output ports and input ports.
However, due to the large number of electrical channels and the very high frequencies employed in modern DWDM optical networks, the use of multiple conductive wire bonds is approaching its practical limits. Such limits for example may arise from the space requirements for multiple connective wire bonds, cross-talk or interference between adjacent wire bonds due to their close proximity to one another and the very high-frequency of the electric signals, impedance-mismatch induced signal deterioration due to reflections of the high-frequency signals carried by the wire bonds.
To that end, what is needed is a device and method to more efficiently interconnect modulator drivers and modulators incorporated into PICs of optical networks and optical signal detectors and receiver amplifiers, while at the same time minimizing impedance mismatch and heat buildup in the PICs. It is to such interconnect bridge assemblies between a modulator driver and a PIC and/or a PIC and a receiver amplifier that the inventive concepts disclosed herein are directed.